1. Field of the Invention
This invention relates to a method for producing novel reticulated puffed borax having enhanced absorptive capacity for functional compositions.
2. Prior Art
The preparation, properties, and uses of expanded or so-called "puffed" borax, have been described in numerous references. Excellent discussions are set forth in, for example, Technical Service Bulletin No. 27 (revised September 1971), of Borax Consolidated Limited of London, England; in Bulletin 0171, entitled "Puffed Borax" issued October 1973 by Kerr-McGee Chemical Corp., Okalahoma City, OK; and in an article by R. C. Rhees and H. H. Hammar entitled "Puffed Borax" appearing in Soap And Chemical Specialties, Vol. XLII, for January 1966 at pages 58-61 and 118-120.
Among other things, these references describe known prior art processes wherein particulate borax pentahydrate particles are rapidly heated to above the melting temperature of the pentahydrate, whereat the borate dissolves in its own water of hydration and the solution erupts through the partially dehydrated crystal surface, resulting in the puffed product.
The resultant puffed product consists of low density particles or beads, which have a high surface area and include large quantities of voids. Generally, each particle is comprised of a plurality of expanded cells adjacent to and attached to each other. By virtue of such structure, large quantities of liquids and/or solids can be loaded onto the expanded borax, rendering such product useful as a bulk carrier in numerous applications. For example, organics such as trichloroethylene, cyclohexanone or pentachlorophenol, and other functional type compositions such as non-ionic, cationic, and anionic surfactants, can be loaded at very high concentrations onto the puffed borax, with the product still retaining its free flowing characteristics. This renders the puffed borax very useful in such diverse compositions as dairy cleaners, fabric softeners, bath additives, etc.
Various techniques have been utilized in the past to effect the desired heating of the borax feed material to produce the puffed borax, see for example, U.S. Pat. No. 4,031,345 to D'Souza, British Pat. No. 629,171, U.S. Pat. No. 3,454,357 Rhees and Hammar, and U.S. Pat. No. 3,882,034 to Gibbons.
Additionally, in applicant's aforementioned parent application U.S. Ser. No. 358,050, an improved method and apparatus are described for producing a puffed borax product having superior particle strength and improved uniformity of hydration and puff ratio. The invention involves introducing particles of borax having a given particle size distribution into a downwardly flowing, slowly moving, laminar airstream in a vertical tower, as a horizontally dispersed sheet of particles. The vertical tower is essentially a conventional spray drying tower which has been suitably modified for use in the process. The airstream is heated sufficiently to remove part of the water of hydration, but not to such a degree as would completely remove the water of hydration or fuse the borax. The borax particles, carried by the airstream, are carried downstream and gravitationally separated. The particles are found to have a more uniform puffing ratio.
Even with applicant's improved process, it is still desirable to have a puffed borax having an enhanced absorptive capacity for functional compositions absorbed therein.
In some of the aforementioned references, rehydration of puffed borax is discussed. Generally, however this involves the addition of the puffed borax to bulk aqueous solutions as opposed to the controlled addition of water by spraying or the like. Additionally these references do not teach or suggest that such rehydration of puffed borax enhances the absorptive capacity of the borax.
In accordance with the foregoing, it may, therefore, be regarded as an object of the present invention, to provide a method for enhancing the absorptive capacity of functional compositions into puffed borax particles.
A further object of this invention is to provide reticulated puffed borax particles having enhanced absorptive capacity for functional compositions.
A still further object of this invention is to provide a method for enhancing the absorptive capacity of functional compositions into puffed borax, the puffed borax being a free-flowing, agglomerate free borax, in which the particles of different sizes are puffed to a more uniform ratio, and have a uniformly high bead strength.